On 5/18/2011 7:11 PM, Gavin Flower wrote:

We're getting pretty OT here...

What obvious thing have I done, or not done, here?

What should I do now?

(I am not panicking, because I can always revert back...)

I tried to implement you suggestion, 

# swapoff -a
# dd if=/dev/zero of=/swapfile1 bs=1K count=16M
16777216+0 records in
16777216+0 records out
17179869184 bytes (17 GB) copied, 119.642 s, 144 MB/s
# mkswap /swapfile1
Setting up swapspace version 1, size = 16777212 KiB
no label, UUID=9afbf206-9a79-45b8-ad4b-148f71c440d7

17GB is a bit ridiculous for swap, especially on a single user machine.

# swapon /swapfile1
# cp /etc/fstab /etc/fstab-20110519

in
/etc/fstab
I replaced
UUID=654f3b90-ed2c-4de6-9f2a-e2ad65fd1af1 swap                    swap    defaults        0 0
by
/swapfile1                                swap                    swap    defaults        0 0

The log message for the swapon was:
May 19 11:27:38 saturn kernel: [38075.451398] Adding 16777212k swap on /swapfile1.  Priority:-1 extents:159 across:24068092k 

Looks good.

However, it failed to hibernate.  The log messages were:
May 19 11:44:43 saturn kernel: [39043.115385] sd 1:0:0:0: [sdb] Starting disk
May 19 11:44:43 saturn kernel: [39043.128453] sd 2:0:0:0: [sdc] Starting disk
May 19 11:44:43 saturn kernel: [39043.140116] sd 3:0:0:0: [sdd] Starting disk
May 19 11:44:43 saturn kernel: [39043.150889] sd 5:0:0:0: [sde] Starting disk
May 19 11:44:43 saturn kernel: [39043.165729] PM: thaw of devices complete after 756.642 msecs
May 19 11:44:43 saturn kernel: [39043.322491] PM: Saving image data pages (809839 pages) ... done
May 19 11:44:43 saturn kernel: [39094.461575] PM: Wrote 3239356 kbytes in 51.13 seconds (63.35 MB/s)
May 19 11:44:43 saturn kernel: [39094.465739] PM: S
May 19 11:44:43 saturn kernel: [39094.482407] PM: Swap header not found!
May 19 11:44:43 saturn kernel: [39094.485188] |
May 19 11:44:43 saturn kernel: [39094.706731] Restarting tasks ... done.
May 19 11:44:43 saturn NetworkManager[1501]: <info> wake requested (sleeping: yes  enabled: yes)
May 19 11:44:43 saturn NetworkManager[1501]: <info> waking up and re-enabling...
May 19 11:44:43 saturn NetworkManager[1501]: <info> (eth0): now managed

I've never used hibernation, but a quick Google search gives lots of
information on this.  Google "linux swap file hibernate".  I read one
thread from 2008, in which folks easily solved this with a kernel update
or switching the filesystem where they stored the swap file.  I would
think 3 years later any bugs in the hibernation code have been squashed
and this should work flawlessly.

What kernel/distro version are you running?  Anything recent should be
able to handle hibernation to a swap file.

-- 
Stan